Re: [Gretl-users] import data via odbc

On Fri, 11 Mar 2011, Leon Unger wrote: > recently I tried to read in several series via odbc *including > one dummy* series and I forgot to change its entries from "No" > and "YES" to "0" and "1". > However, SQL retrieved for all series the correct number of > observations.*BUT ALL SERIES* were corrupted. That's why two > thoughts come up: > > 1) I know from importing STATA files that GRETL changes string > entries to number entries. Does GRETL use information provided > by the STATA file, or does it this job by itself? If yes, would > it be possible to add this functionality to the odbc read in > process? > > 2) If one has always to provide numerical entries and e.g. one > series is not correcltly specified then actually only this > series should be corrupted. As I said previously, I agree with Jack Lucchetti's comment that getting an ODBC import right is really the responsbility of the gretl user. But I also said that it was gretl's responsibility to avoid crashing on an incorrect SQL query. I've now investigated further, and I'm less inclined to think there's a bug in gretl's handling of this issue. Gretl can convert string-valued variables from Stata dta files into numerical values because a dta file contains a clear specification of the "original" type of each variable. But things are different with ODBC. One uses the function SQLBindCol() to tell ODBC what data type one wants from each data column (and for all actual data columns gretl specifies the type SQL_C_DOUBLE). It's then ODBC's job to convert whatever type comes out of the db into what was requested. As a test, I constructed a dummy db using mysql, with one "real" numerical data column and one column containing "yes" and "no" strings. I then used gretl to read in those two variables via unixODBC. What I got was basically what you'd expect: the numerical series came in OK, and the "yes"/"no" column came in as a series of zeros (zero being the default when no numeric conversion is possible). If you're getting general data corruption when one of the data columns contains strings, then (a) it might help if you were to give us an exact recipe for reproducing the problem, but (b) maybe your bug report should go to Microsoft Corp? Allin Cottrell _______________________________________________ Gretl-users mailing list Gretl-users(a)lists.wfu.edu http://lists.wfu.edu/mailman/listinfo/gretl-users